If you haven't already heard about Wolfram Alpha, you should watch the introduction to all the amazing things it can do.
This is going to be one of those tools where the trick is getting used to thinking of it when there's a situation it can answer. At first, you'll sit and stare at it thinking "what can I ask it?" and have a hard time thinking of things that aren't just makework; and then there'll be times you have a question it could answer but you won't think of using it to find out. Then you'll either gradually get used to the idea of consulting it at the right times, or you won't. In the latter case, you'll conclude that it was never anything but a gimmick. In the former, it'll transform how you do things and what you can do. We went through this with IMDB, with Yahoo, with AltaVista, with Google, and with Wikipedia; but I think the gap is going to be even bigger in this case, because the range of things Wolfram Alpha can do is so much more vertical (deeper but narrower) and it's harder to sum up in a single concept.
Incidentally, I ran into another small advantage Opera has over Firefox when this came out. In Opera, adding a new search engine is as simple as right-clicking and choosing a menu option, and you can do it the instant you find any search field in any site. It only makes sense; if you are on a search form, Opera already knows everything it needs to useit when you point to a text field. (It might not be able to use all the features, but then, neither will the built-in search field in the browser anyway.) But in Firefox the only way to add a search engine is if someone has taken the time to make an add-on that adds it. Fortunately, Wolfram Alpha is a big enough deal that there already is one available. But the limitation seems senseless.